Here's why:

* Neutrons are neutral: Neutrons, the particles found in the nucleus of atoms alongside protons, have no electric charge.

* Antiparticles have opposite charges: Antiparticles are the "antimatter" counterparts of normal particles. While they have the same mass as their corresponding particles, they have opposite charges.

* Antineutrons are the antiparticle of neutrons: Since neutrons have no charge, their antiparticles, antineutrons, also have no charge.